Currently (early 2014) there are almost 8 million active witnesses of Jehovah in the world, preaching in almost 300 different lands, and offering literature, videos, and Bible studies in 100's of different spoken and signed languages.
They willingly do this in obedience to Jesus' command at Matthew 28:19,20, volunteering their own money, time and energy to contact as many people as possible with the good news of God's Kingdom and offering free home Bible studies.
In 2012 well over 7 and a half million members were actively witnessing worldwide about God's Kingdom and his righteousness. (Matthew 6:33, 24:14; 28:19,20)
I remember a friend asking me, on finding out I was going to a small Assembly, how many were going to be there. He thought about 150. He was a little surprised when I said the figure would be over 1,000 from ten different congregations. He had thought that, although we seem to be at people's doors frequently, to be very few in number. While that is true in some places, in other areas the Witnesses are well represented numerically.
In 2011, 7,659,019 publishers of the good news reported from 236 lands and islands. (In comparison, there were 205 countries represented at the Olympics recently.) All these Christians give willingly of their time and resources to try and help people from all backgrounds to hear the Bible's message. Literature is now available in 630 languages including for those who are blind or deaf.
In 2010 there were over 18 million worldwide in attendance at the annual observance of the memorial of the death of Jesus Christ.
As of September 2009, the exact number was 7,313,173.
When I first heard Bible truth from the witnesses in the year 1995, there were only 3 million active witnesses worldwide (if I remember correctly).
Jehovah's witnesses do not count in their totals the number of meeting attenders or visitors, but only those who are actively sharing the good news about God's Kingdom (ruled by Jesus Christ) and witnessing regularly about their Grand Creator and Instructor, Almighty Jehovah God. (Psalm 83:18)